mcdiscordbot/MinecraftDiscordBot/TimeoutTokenProvider.cs

namespace MinecraftDiscordBot;

public class TimeoutTokenProvider : ITokenProvider {
    public TimeoutTokenProvider(int instanceId, int timeoutSeconds, ICipher? cipher = null) {
        InstancePrefix = Convert.ToHexString(BitConverter.GetBytes(instanceId));
        _timeout = timeoutSeconds;
        _cipher = cipher ?? new AesCipher();
    }
    private readonly ICipher _cipher;
    private readonly int _timeout;
    public string InstancePrefix { get; }
    public bool VerifyToken(string token) {
        if (!token.StartsWith(InstancePrefix)) return false;
        token = token[InstancePrefix.Length..];
        byte[] data;
        try {
            data = _cipher.Decrypt(Convert.FromHexString(token));
        } catch (Exception e) {
            Program.LogError("TokenProvider", e);
            return false;
        }
        var when = DateTime.FromBinary(BitConverter.ToInt64(data, 0));
        return when >= DateTime.UtcNow.AddSeconds(-_timeout);
    }
    public string GenerateToken() {
        var time = BitConverter.GetBytes(DateTime.UtcNow.ToBinary());
        var key = Guid.NewGuid().ToByteArray();
        var token = InstancePrefix + Convert.ToHexString(_cipher.Encrypt(time.Concat(key).ToArray()));
        return token;
    }
}

public interface ITokenProvider {
    string GenerateToken();
    bool VerifyToken(string token);
}